Method and apparatus for changing the direction of fluid flow in fuel cell flow fields

Abstract

A fuel cell includes an electrolyte electrode assembly and a pair of first and second separators. First through fourth oxygen-containing gas holes, first through fourth coolant holes, and first through fourth fuel gas holes extend through the fuel cell. The first through fourth oxygen-containing gas holes are selectively used as oxygen-containing gas supply ports or oxygen-containing gas discharge ports to change the flow direction of an oxygen-containing gas in an oxygen-containing gas flow field continuously.

1. A fuel cell including an electrolyte electrode assembly, and a pair of separators for sandwiching said electrolyte electrode assembly, said electrolyte electrode assembly including a pair of electrodes and an electrolyte interposed between said electrodes, said fuel cell further comprising:
 a plurality of fluid holes extending through said fuel cell for passing a fluid, which comprises at least one of an oxygen-containing gas, a fuel gas, and a coolant, through said fuel cell, wherein the plurality of fluid holes includes at least three fluid holes that are required for passing the fluid; 
 at least one fluid flow field connectable to said fluid holes for causing said fluid to flow along a surface of said electrode; 
 a switching mechanism for switching a supply pipe selectively to connect to one of said fluid holes to use as a fluid supply port for supplying said fluid to said fluid flow field or switching a discharge pipe selectively to one of said fluid holes to use as a fluid discharge port for discharging said fluid from said fluid flow field; and 
 a controller that controls the switching mechanism to select a first fluid hole from said fluid holes as the fluid supply port and a second fluid hole from said fluid holes as the fluid discharge port, and to switch the fluid supply port from the first fluid hole or the fluid discharge port from the second fluid hole to a third fluid hole to change the flow direction of said fluid in said fluid flow field, while maintaining continuous flow of said fluid. 
 
     
     
       2. A fuel cell according to  claim 1 , wherein each of said fluid holes is used as said fluid supply port, used as said fluid discharge port, or not used as a fluid port by switching operation of said switching mechanism, and at least one fluid hole is used as said fluid supply port and at least one fluid hole is used as said fluid discharge port. 
     
     
       3. A fuel cell according to  claim 1 , wherein said fluid holes include at least one inner hole defined in said electrodes. 
     
     
       4. A fuel cell according to  claim 1 , wherein said fluid flow field is defined by an embossed structure on said separator. 
     
     
       5. A fuel cell according to  claim 4 , wherein said embossed structure includes guide ribs. 
     
     
       6. A fuel cell according to  claim 1 , wherein said fuel cell includes at least two fluid flow fields, and said fluid flow fields include a fuel gas flow field and an oxygen-containing gas flow field for being supplied with a fuel gas and an oxygen-containing gas, respectively, which flow as counterflows, respectively, through said fuel gas flow field and said oxygen-containing gas flow field. 
     
     
       7. A fuel cell according to  claim 6 , wherein said fluid flow fields further include a coolant flow field for being supplied with a coolant flowing through said coolant flow field, the coolant flows parallel to said oxygen-containing gas. 
     
     
       8. A fuel cell according to  claim 1 , wherein said electrolyte electrode assembly and said separators are stacked vertically.